Methods and Apparatus for Scatter Correction for Cbct System and Cone-Beam Image Reconstruction

1. A computer implemented method comprising: capturing an image of an object using an x-ray source emitting x-rays toward the object and a detector capturing image data of the object; modifying the captured image to correct artifacts therein caused by scattering of the x-rays, the step of modifying the image including: determining a scatter distribution of the x-rays in an air region near the object using the captured image of the object; estimating a scatter intensity of the x-rays within the object based on the determined scatter distribution; and subtracting the estimated scatter intensity of the x-rays from the captured image to provide the modified image.

2. The computer implemented method of claim 1 , further comprising: modulating the estimated scatter intensity of the x-rays based on a modulator, and determining the modulator as a function of an inverted scaled image value; and determining the inverted scaled image value as a function of a scaling factor.

3. The computer implemented method of claim 2 , further comprising: converting the captured image data of the object into corresponding image data in log space; searching for a highest intensity image datum in the log space across all the image data; determining a scatter-to-primary ratio based on the highest intensity image datum; and determining the scaling factor as a function of the scatter-to-primary ratio, the image data in the log space, the captured image data of the object, and the estimated scatter intensity of the x-rays within the object.

4. The computer implemented method of claim 3 , wherein the step of determining the scaling factor includes determining the scaling factor from the captured image of the object, and the step of determining the inverted scaled image value includes dividing the image data in log space by the scaling factor.

5. The computer implemented method of claim 1 , wherein the step of estimating the scatter intensity of the x-rays within the object includes performing a linear interpolation of the determined scatter distribution of the x-rays in the air region near the object.

6. The computer implemented method of claim 5 , wherein the step of determining the scatter distribution of the x-rays in the air region near the object includes determining the scatter distribution of the x-rays in an air gap between the x-ray source and the object.

7. The computer implemented method of claim 6 , further comprising capturing a plurality of images of the object, wherein the step of determining the scatter distribution of the x-rays in an air gap between the x-ray source and the object is performed for each of the captured images of the object.

8. The computer implemented method of claim 2 , wherein a magnitude of the modulator is proportional to a percentage of scattered x-rays within the object.

9. The computer implemented method of claim 1 , further comprising capturing a plurality of images of the object and performing the step of modifying on each of the captured plurality of images, including processing the plurality of the modified images to reconstruct a 3D volume image of the object, storing the 3D volume image of the object in a computer accessible memory, and displaying the 3D volume image.

10. In a method of image processing of a radiographic digital image of a subject, executed at least in part on a computer, the improvement comprising: modifying the radiographic digital image to correct artifacts in the image caused by scattering of x-rays, the step of modifying including: determining a scatter distribution of the xrays in an air region near the subject using the radiographic digital image of the subject; estimating a scatter intensity of the x-rays within the subject based on the determined scatter distribution; and subtracting the estimated scatter intensity of the x-rays from the radiographic digital image to provide the modified radiographic digital image.

11. The method of claim 10 , further comprising: converting the image of the subject into corresponding image data in log space; searching for a highest intensity image datum in the log space; determining a scatter-to-primary ratio based on the highest intensity image datum; and processing the image of the subject as a function of the scatter-to-primary ratio, the image data in the log space, and the estimated scatter intensity of the x-rays within the subject.

12. The method of claim 10 , wherein the step of estimating the scatter intensity of the x-rays within the subject includes performing a linear interpolation of the determined scatter distribution of the x-rays in the air region near the subject.

13. The method of claim 12 , further comprising modifying a plurality radiographic digital images of the subject, wherein the step of determining the scatter distribution is performed for each of the plurality of radiographic digital images of the subject.

14. The method of claim 13 , further comprising processing the plurality of the radiographic digital images of the subject to reconstruct a 3D volume image of the subject, storing the 3D volume image of the subject in a computer accessible memory, and displaying the 3D volume image of the subject.

15. A computer implemented method comprising: capturing an image of an object using an x-ray source emitting x-rays toward the object and a detector capturing image data of the object; modifying the captured x-ray image to correct artifacts in the image caused by scattering of the x-rays, the step of modifying the image including: determining a scatter distribution of the x-rays in an air region near the object; determining a first scatter intensity of the x-rays within a shadow of the object based on the determined scatter distribution; determining a final scatter intensity of the x-rays within the shadow of the object, including modulating the first scatter intensity of the x-rays based on a modulator; and subtracting the determined final scatter intensity of the x-rays from the captured x-ray image to provide the modified x-ray image.

16. The computer implemented method of claim 15 , further comprising: determining the modulator as a function of an inverted scaled image value; and determining the inverted scaled image value as a function of a scaling factor.

17. The computer implemented method of claim 16 , further comprising: converting the captured image data of the object into corresponding image data in log space; searching for a highest intensity image datum in the log space across the image data of the object; determining a scatter-to-primary ratio based on the highest intensity image datum; and determining the scaling factor as a function of the scatter-to-primary ratio, the captured image data in the log space, the captured image data of the object, and the first scatter intensity of the x-rays within the shadow of the object.

18. The computer implemented method of claim 17 , wherein the step of determining the scaling factor includes determining the scaling factor from the captured image of the object, and the step of determining the inverted scaled image value includes dividing the image data in log space by the scaling factor.

19. The computer implemented method of claim 15 , wherein the step of determining the first scatter intensity of the x-rays within the shadow of the object includes performing a linear interpolation of the determined scatter distribution of the x-rays in the air region near the object.

20. The computer implemented method of claim 19 , wherein the step of determining the scatter distribution of the x-rays in the air region near the object includes determining the scatter distribution of the x-rays in an air gap between the x-rays source and the object.

21. The computer implemented method of claim 15 , wherein a magnitude of the modulator is proportional to a percentage of scattered x-rays within the shadow of the object.

22. In a method of digital radiographic image processing of an image of a subject, executed at least in part on a computer, the improvement comprising: modifying the radiographic image of the subject to correct artifacts in the image caused by scattering of x-rays, the step of modifying the image including: determining a scatter distribution of the x-rays in an air region near the subject; determining a first scatter intensity of the x-rays within a shadow of the subject based on the determined scatter distribution; determining a final scatter intensity of the x-rays within the shadow of the subject; and subtracting the determined final scatter intensity of the x-rays from the radiographic image of the subject to provide the modified radiographic image of the subject.

23. The method of claim 22 , further comprising: converting the captured radiographic image of the subject into corresponding image data in log space; searching for a highest intensity image datum in the log space; determining a scatter-to-primary ratio based on the highest intensity image datum; and processing the captured radiographic image of the subject as a function of the scatter-to-primary ratio, the captured image data converted into the log space, and the first scatter intensity of the x-rays within the shadow of the subject to provide the modified radiographic image of the subject.

24. The computer implemented method of claim 22 , wherein the step of determining the first scatter intensity of the x-rays within the shadow of the subject includes performing a linear interpolation of the determined scatter distribution of the x-rays in the air region near the subject.